startlxde: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/startlxde - from package: lxde-common

You may install the required package with command apt-get install {package}

Error in other languages:
startlxde: bevel nie gevind nie
startlxde: comandă negăsită
startlxde: comando não encontrado
startlxde: commande introuvable
startlxde: command not found
startlxde: käsku ei ole
startlxde: không tìm thấy lệnh
startlxde: komanda nerasta
startlxde: Kommando nicht gefunden.
startlxde: kommandot finns inte
startlxde: komut yok
startlxde: nie znaleziono polecenia
startlxde: níor aimsíodh an t-ordú
startlxde: no se encontró la orden
startlxde: no s'ha trobat l'ordre
startlxde: opdracht niet gevonden
startlxde: parancs nem található
startlxde: perintah tidak ditemukan
startlxde: príkaz nenájdený
startlxde: příkaz nenalezen
startlxde: команда не найдена
startlxde: командата не е открита
startlxde: 命令找不到
startlxde: コマンドが見つかりません